Chimney cowl



Sept. 10, 1957 2,805,616

P. ROTH CHIMNEY COWL Filed De. 10. 1954 INVENTOR. I ATF/CK Q5 TH ATTORNEY Patented Sept. 1957 ice This invention relates to a chimney cowl, and more particularly to a chimney cowl especially adapted for insertion on chimneys of, residences having gas and oil furnaces for preventing excessive chimney draft and for stopping downdraft and entry of water inside the chimney.

An outstanding disadvantage arising from the operation of conventional gas furnaces, oil furnaces and space heaters in homes and factories has been the fact that a large percentage of heat goes up the chimney and is wasted because of the excessive draft provided by'the chimney which causes air to flow too fast through the heat exchanger. Thus the home owner or customer of the gas or oil furnace does not receive the full B. t. u. output of the furnace as rated by the American Gas Association. Gas bills are as much as 25 percent higher than they should be. Also the chimney duct is cooled causing condensation and rusting of the duct system such as the smoke pipe. Moreover, in conventional chimneys, even those having chimney cowls, there is usually an excessive downdraft which tends to blow out furnace pilot lights as well as cause rattling and banging of. dampers or control gates, such as used in barometric chimney draft controls.

A disadvantage of known types of chimney co'wls is that they do not overcome the above mentioned difiiculties, moreover they are generally fitted to very close tolerances inside the chimney duct, making their insertion diflicult, particularly in case of the usual irregular surfaces inside the chimney such as caused by excessive mortar projecting from'the inner walls-also they are not easily attachable to or detachable from the chimneys, nor adapted to fit varying sizes of chimneys.

Chimneys are generally made oversize rather than undersize, therefore necessarily require some reduction in the amount of draft created thereby for most etficient operation of the heating system.

An object of my invention is to provide a novel chimney cowl which is of such construction as to eliminate the above named disadvantages, and which is of relatively simple and inexpensive construction, as well as being easily and quickly attachable to or detachable from chimneys of varying sizes.

A more specific object of my invention is to provide a sheet metal chimney cowl of such construction as to prevent excessive chimney drafts and downdrafts, and thus avoid excessive heat losses as well as preventing blowing out of the pilot and hanging of control dampers or gates in the furnace, also for preventing water from entering and running down inside the chimney, also to provide a sufficiently heated column of air so as to prevent condensation and rusting of the ducts, .such as the smoke pipe and cowl.

Other objects and advantages of the present invention will become apparent from a study of the following description taken with the accompanying drawing wherein:

Figure l is a perspective view of a top portion of a chimney showing a chimney cowl installed thereon and embodying the principles of my invention;

Figure 2 is a longitudinal cross-sectional view taken along line IIII of Figure l; and

Figure 3 is an enlarged cross-sectional view of a modified form of resilient bracket construction somewhat similar to that shown in Figure 2.

Referring more particularly to Figure 1, numeral 1 denotes a chimney of ordinary construction such as used in residences, having detachably mounted thereon a chimney cowl, denoted generally by numeral 2, embodying the principles of the present invention. The cowl 2 comprises a cone or hood 3 preferably of sheet metal which is suspended by four (or any other number of) support arms 4 formed of metal strips. The outer ends of arms 4 are bent and integrally secured, such as by welding or riveting, to the cone portion and the inner ends thereof bcing'bent at an angle of and likewise integrally secured to the top of a stub or pipe 5 of sheet metal. If desired, a vertical slot of about 1 inch height may be put in the inner bent portion of arm 4 or perhaps in the top of pipe 5 so as to permit a limited amount of adjustment of the height of the cone, but not sufficiently to abnormally reduce the opening between the cone and pipe. It will be noted that the bottom edge of the cone projects below the top edge of pipe 5 so as to prevent lateral currents of wind from blowing directlyinto the chimney and causing excessive downdrafts. vFurthermore, such lateral currents of wind will strike against cowl portion 3 and provide a downward thrust to the cowl instead of blowing it off the chimney.

A base plate 6, of rectangular outline and preferably of sheet metal having a circular cut out portion, is tack welded, riveted or otherwise integrally secured to the bottom. edge portion of pipe 5 preferably below a, concave annular corrugation 5a of pipe Sas shown more clearly in igure 3. Base plate 6 may be a flat sheet, but is preferably formed so as to have a slightly convex top surface. This shape is obtained by bowing upwardly a pieceof sheet metal by pressing creases 6a along diagonal lines with the edge portions upwardly bowed. T his convex shape of base plate 6 provides drainage of rain away from the cowl and prevents its entry into the chimney;

Underneath base plate 6 there is tack welded or otherwise integrally secured a pair of oppositely disposed resilient brackets 7, which may be made of sheet metal or spring steel, both having outwardly bent leg portions 7a which are adapted to anchor the lower edge of a mortar joint 8 or other projection extending inwardly from the inner wall or duct 9 of the chimney. The leg portions 7a are longer than the upper bent portions of brackets 7 which are attached to base plate 6 and may be of the order of /2 inch long.

In assembly, the resilient brackets 7 are sprung toward each other so as to readily clear any inward projections extending from the inner wall 9 of the chimney, and the cowl is lowered into place. As the cowl is being lowered resilient brackets 7 will readily yield and ride over such inward projections until finally the lower edge portion 7a thereof will latch onto the bottom of the lowermost inward projection, such as that provided by the edges of a brick course or by a projecting mortar line. Thus a very secure anchor is obtained for holding base plate 6 in place and which will prevent blowing off of the cowl as a consequence of strong winds. And as stated previously, by having the lower edge of cone 3 extend below the top edge of pipe 5, laterally blowing winds'will not blow directly into the chimney and cause excessive downdrafts, also such arrangement forms somewhat of a trap for the heated air column rising through the chimney to cause the chimney to become more heated and thus prevent condensation and rusting of the duct system, such as the furnace smoke pipe, pipe 5, etc.

Figure 3 shows a modification of the chimney brackets 3 7 shown in Figure 2 which embodies making the brackets of separate attachable parts 7c, 7d which may be attached together by screws or bolts 7e extending through vertical slots to adjust the length of brackets 7. This arrangement also enables packaging of the cowl assembly in a smaller package unit for shipment.

It will be noted that the cowl assembly is a rather shallow one as comparedto conventional cowls. Hood 3 is only about 7 inches high and may extend about a half inch or so below the topof pipe 5. Pipe 5 may also be 5", 6" or 7" in diameter and about 7 inches high, or slightly more or less. The hood is adapted to fit chimneys of varying sizes and eliminates the necessity of close tolerances. The hood may fit chimneys of 7, 8 or 9 incheswide, and maybe made in one or more sizes to cover diifereutranges of chimney sizes.

The present cowl reduces by as much as five minutes the time necessary for a furnace or building to heat up to a predetermined temperature, that is, to the temperature limit of the furnace as determined by the setting of an aquastat, while a room thermostat calls for heat. Thus the heating system is made more quickly responsive to the room thermostat and room temperatures are kept more constant. The blower or water pump starts quicker.

Thus it will be seen that I have provided an eflicient chimney cowl which is of relatively simple and inexpensive construction, which can be readily attached to or detached from a chimney irrespective of the wide range of sizes and irregular surfaces of the inner duct or flue, as frequently encountered; furthermore I have provided a cowl arrangement involving a construction to prevent excessive chimney drafts and excessive downdrafts so as to prevent waste of heat, condensation and rusting of the duct system and at the same time preventing blowing out of pilots, rattling of controlflapper valves orgates and other objectional features resulting from downdrafts; furthermore I have provided a cowl which is particularly suitable for chimneys used with gas and oil furnaces and the like, and which aflords savings, of as much as 25 per cent in fuel bills as well as greatly improving the efficiency and operating performanceof thefurnace.

While I have illustrated and described an embodiment said cowl comprising a cone with its vertex uppermost and forming the top portion of the cowl, a cylindrical sheet metal pipe extending vertically and forming the central portion of the cowl, horizontal supporting strips attached to the top portion of the pipe and the lower surface of said cone for mounting the cone in spaced relationship therewith and for permitting chimney drafts to move upwardly through the pipe and downwardly of the cone through the spaces formed between said supporting strips, and whereby lateral winds will not directly enter the cowl and will cause a downward thrust on said cowl, a rectangular base plate having a circular hole cut out centrally thereof which is tightly fitted against the bottom edge of said pipe for mounting on top of a chimney, and a pair of oppositely disposed brackets in the form of long fiat resilient strips flared in a downward and outward direction throughout their entire length and having outwardly and upwardly bent lower edges adapted to anchor against the bottom portions of projections extending inwardly of the inner wall of the chimney, the upper ends of said brackets being secured to the bottom surface of said base plate.

2. A chimney cowl as recited in claim 1 wherein the bottom portion of said pipe has an outwardly bowed circular rib portion adapted to rest on the circular cut out hole in said base plate and having an outwardly extending flange below said rib portion which engages and underlies said base plate.

3. A chimney cowl as recited in claim 1 wherein said brackets are made of'two relatively adjustable parts attachable together by fastening means and wherein the lower outwardly bent anchoring end portions of the brackets are of the order of /2" inch long so as to form of my: invention, it will be understood that thisis by way 1 reliable anchors underneath projections in the inner walls of the chimney.

References Cited in the fileof this patent UNITED STATES PATENTS 179,147 Auld June 27, 1876 191,230 Entwisle 'May 29, 1877 281,645 Rosenstar "July 17, 1883 292,505 Petersen Jan. 29, 1884 312,918 Steen Feb. 24, 1885 638,172 Burress Nov. 28, 1899 878,811 Lincoln Feb. 11,1908 1,103,734 Belknap July 14, 1914 I 1,854,515 Iackes Apr. 19, 1932 FOREIGN PATENTS 7,762 Great Britain .a June 2, 1900 

